diff --git a/packages/ember-cli-fastboot/fastboot/instance-initializers/fetch.js b/packages/ember-cli-fastboot/fastboot/instance-initializers/fetch.js
new file mode 100644
index 000000000..9fbcda4e5
--- /dev/null
+++ b/packages/ember-cli-fastboot/fastboot/instance-initializers/fetch.js
@@ -0,0 +1,9 @@
+function initialize(instance) {
+  let { request } = instance.lookup('service:fastboot');
+  fetch.__fastbootRequest = request;
+}
+
+export default {
+  name: 'fastboot:fetch', // `ember-fetch` addon registers as `fetch`
+  initialize,
+};
diff --git a/packages/fastboot/src/sandbox.js b/packages/fastboot/src/sandbox.js
index 75c413734..e462a0693 100644
--- a/packages/fastboot/src/sandbox.js
+++ b/packages/fastboot/src/sandbox.js
@@ -4,6 +4,9 @@ const chalk = require('chalk');
 const vm = require('vm');
 const sourceMapSupport = require('source-map-support');
 
+const httpRegex = /^https?:\/\//;
+const protocolRelativeRegex = /^\/\//;
+
 module.exports = class Sandbox {
   constructor(globals) {
     this.globals = globals;
@@ -56,27 +59,86 @@ module.exports = class Sandbox {
   }
 
   buildFetch() {
+    let globals;
+
     if (globalThis.fetch) {
-      return {
+      globals = {
         fetch: globalThis.fetch,
         Request: globalThis.Request,
         Response: globalThis.Response,
         Headers: globalThis.Headers,
         AbortController: globalThis.AbortController,
       };
+    } else {
+      let nodeFetch = require('node-fetch');
+      let {
+        AbortController,
+        abortableFetch,
+      } = require('abortcontroller-polyfill/dist/cjs-ponyfill');
+      let { fetch, Request } = abortableFetch({
+        fetch: nodeFetch,
+        Request: nodeFetch.Request,
+      });
+
+      globals = {
+        fetch,
+        Request,
+        Response: nodeFetch.Response,
+        Headers: nodeFetch.Headers,
+        AbortController,
+      };
     }
 
-    let nodeFetch = require('node-fetch');
-    let { AbortController, abortableFetch } = require('abortcontroller-polyfill/dist/cjs-ponyfill');
-    let { fetch, Request } = abortableFetch({ fetch: nodeFetch, Request: nodeFetch.Request });
+    let originalFetch = globals.fetch;
+    globals.fetch = function __fastbootFetch(input, init) {
+      input = globals.fetch.__fastbootBuildAbsoluteURL(input);
+      return originalFetch(input, init);
+    };
 
-    return {
-      fetch,
-      Request,
-      Response: nodeFetch.Response,
-      Headers: nodeFetch.Headers,
-      AbortController,
+    globals.fetch.__fastbootBuildAbsoluteURL = function __fastbootBuildAbsoluteURL(input) {
+      if (input && input.href) {
+        // WHATWG URL or Node.js Url Object
+        input = input.href;
+      }
+
+      if (typeof input !== 'string') {
+        return input;
+      }
+
+      if (protocolRelativeRegex.test(input)) {
+        let request = globals.fetch.__fastbootRequest;
+        let [protocol] = globals.fetch.__fastbootParseRequest(input, request);
+        input = `${protocol}//${input}`;
+      } else if (!httpRegex.test(input)) {
+        let request = globals.fetch.__fastbootRequest;
+        let [protocol, host] = globals.fetch.__fastbootParseRequest(input, request);
+        input = `${protocol}//${host}${input}`;
+      }
+
+      return input;
     };
+
+    globals.fetch.__fastbootParseRequest = function __fastbootParseRequest(url, request) {
+      if (!request) {
+        throw new Error(
+          `Using fetch with relative URL ${url}, but application instance has not been initialized yet.`
+        );
+      }
+
+      // Old Prember version is not sending protocol
+      const protocol = request.protocol === 'undefined:' ? 'http:' : request.protocol;
+      return [protocol, request.host];
+    };
+
+    let OriginalRequest = globals.Request;
+    globals.Request = class __FastBootRequest extends OriginalRequest {
+      constructor(input, init) {
+        input = globals.fetch.__fastbootBuildAbsoluteURL(input);
+        super(input, init);
+      }
+    };
+
+    return globals;
   }
 
   runScript(script) {
diff --git a/test-packages/basic-app/app/routes/fetch.js b/test-packages/basic-app/app/routes/fetch.js
index 6c6c2bfb5..475238b15 100644
--- a/test-packages/basic-app/app/routes/fetch.js
+++ b/test-packages/basic-app/app/routes/fetch.js
@@ -1,5 +1,6 @@
 import Route from '@ember/routing/route';
 import { assert } from '@ember/debug';
+import { hash } from 'rsvp';
 
 export default class FetchRoute extends Route {
   beforeModel() {
@@ -11,7 +12,29 @@ export default class FetchRoute extends Route {
   }
 
   async model() {
-    let response = await fetch('https://api.github.com/users/tomster');
-    return response.json();
+    let [
+      absoluteURL,
+      absoluteRequest,
+      protocolRelativeURL,
+      protocolRelativeRequest,
+      pathRelativeURL,
+      pathRelativeRequest,
+    ] = await Promise.all([
+      fetch('http://localhost:45678/absolute-url.json'),
+      fetch(new Request('http://localhost:45678/absolute-request.json')),
+      fetch('//localhost:45678/protocol-relative-url.json'),
+      fetch(new Request('//localhost:45678/protocol-relative-request.json')),
+      fetch('/path-relative-url.json'),
+      fetch(new Request('/path-relative-request.json')),
+    ]);
+
+    return hash({
+      absoluteURL: absoluteURL.json(),
+      absoluteRequest: absoluteRequest.json(),
+      protocolRelativeURL: protocolRelativeURL.json(),
+      protocolRelativeRequest: protocolRelativeRequest.json(),
+      pathRelativeURL: pathRelativeURL.json(),
+      pathRelativeRequest: pathRelativeRequest.json(),
+    });
   }
 }
diff --git a/test-packages/basic-app/app/templates/fetch.hbs b/test-packages/basic-app/app/templates/fetch.hbs
index 465f670fb..be5717f19 100644
--- a/test-packages/basic-app/app/templates/fetch.hbs
+++ b/test-packages/basic-app/app/templates/fetch.hbs
@@ -1 +1,6 @@
-{{@model.login}}
\ No newline at end of file
+{{@model.absoluteURL.response}}
+{{@model.absoluteRequest.response}}
+{{@model.protocolRelativeURL.response}}
+{{@model.protocolRelativeRequest.response}}
+{{@model.pathRelativeURL.response}}
+{{@model.pathRelativeRequest.response}}
\ No newline at end of file
diff --git a/test-packages/basic-app/public/absolute-request.json b/test-packages/basic-app/public/absolute-request.json
new file mode 100644
index 000000000..9e22df1aa
--- /dev/null
+++ b/test-packages/basic-app/public/absolute-request.json
@@ -0,0 +1,3 @@
+{
+    "response": "absolute-request"
+}
\ No newline at end of file
diff --git a/test-packages/basic-app/public/absolute-url.json b/test-packages/basic-app/public/absolute-url.json
new file mode 100644
index 000000000..5be641f21
--- /dev/null
+++ b/test-packages/basic-app/public/absolute-url.json
@@ -0,0 +1,3 @@
+{
+    "response": "absolute-url"
+}
\ No newline at end of file
diff --git a/test-packages/basic-app/public/path-relative-request.json b/test-packages/basic-app/public/path-relative-request.json
new file mode 100644
index 000000000..56537c3f6
--- /dev/null
+++ b/test-packages/basic-app/public/path-relative-request.json
@@ -0,0 +1,3 @@
+{
+    "response": "path-relative-request"
+}
\ No newline at end of file
diff --git a/test-packages/basic-app/public/path-relative-url.json b/test-packages/basic-app/public/path-relative-url.json
new file mode 100644
index 000000000..bd94d3de6
--- /dev/null
+++ b/test-packages/basic-app/public/path-relative-url.json
@@ -0,0 +1,3 @@
+{
+    "response": "path-relative-url"
+}
\ No newline at end of file
diff --git a/test-packages/basic-app/public/protocol-relative-request.json b/test-packages/basic-app/public/protocol-relative-request.json
new file mode 100644
index 000000000..aeb56f25d
--- /dev/null
+++ b/test-packages/basic-app/public/protocol-relative-request.json
@@ -0,0 +1,3 @@
+{
+    "response": "protocol-relative-request"
+}
\ No newline at end of file
diff --git a/test-packages/basic-app/public/protocol-relative-url.json b/test-packages/basic-app/public/protocol-relative-url.json
new file mode 100644
index 000000000..ad4fd3664
--- /dev/null
+++ b/test-packages/basic-app/public/protocol-relative-url.json
@@ -0,0 +1,3 @@
+{
+    "response": "protocol-relative-url"
+}
\ No newline at end of file
diff --git a/test-packages/basic-app/test/fetch-test.js b/test-packages/basic-app/test/fetch-test.js
index b46029e40..4a68026fa 100644
--- a/test-packages/basic-app/test/fetch-test.js
+++ b/test-packages/basic-app/test/fetch-test.js
@@ -26,6 +26,11 @@ describe('fetch', function() {
 
     expect(response.statusCode).to.equal(200);
     expect(response.headers['content-type']).to.equalIgnoreCase('text/html; charset=utf-8');
-    expect(response.body).to.contain('tomster');
+    expect(response.body).to.contain('absolute-url');
+    expect(response.body).to.contain('absolute-request');
+    expect(response.body).to.contain('protocol-relative-url');
+    expect(response.body).to.contain('protocol-relative-request');
+    expect(response.body).to.contain('path-relative-url');
+    expect(response.body).to.contain('path-relative-request');
   });
 });